1. Field of the Invention
The present invention relates to a mobile communication system, and more particularly, to a method of transmitting/receiving a broadcast message in a mobile communication system enabling to transmit a broadcast message including a video and the like.
2. Background of the Related Art
Generally, a broadcast message transmitting the same message(data burst message) to all the mobile stations may be transmitted through a common channel such as a paging channel(PCH) or a broadcast control channel (BCCH).
FIG. 1 illustrates a diagram of a transferring form of a broadcast message(data burst message) on a paging channel slot according to a related art.
Referring to FIG. 1, a bass station transmits a data burst message to a broadcast address domain. First of all, the base station informs a terminal of information for transmitting the data burst message using a broadcast page record. In this case, the data burst message is a broadcast message transmitted though a paging channel, and a broadcast page is a record in a general page message so as to inform a mobile station that a broadcast message is transmitted to which location of a slot at a slotted mode.
Illustrated in FIG. 1 is a periodic broadcast paging of which number of the broadcast is 3 as an example.
Namely, enabling a periodic broadcast paging channel, the base station informs the transmission of the broadcast message through broadcast pages #1, #2, and #3 on the broadcast paging channel slot.
Specifically, when all of the broadcast messages is able to be transmitted to be sent on one slot, the broadcast message is transmitted on a first slot of a burst paging cycle. When the number of the broadcast message to be sent is one, the broadcast message is transmitted from the first slot of the burst paging cycle.
In other cases, the broadcast pages are put in the general page message to be sent to the first slot of the burst paging cycle, and each slot location of the corresponding broadcast message is determined in accordance with each location of the respective broadcast pages. Namely, the location of the broadcast message corresponding to the broadcast page of which order of location is n is a 3×n slot.
FIG. 2 illustrates a transfer process of a broadcast message using a paging channel according to a related art.
Referring to FIG. 2, in a transmission of a data burst message using the paging channel, a general page message informs the mobile station of the slot in which the data burst message will be transmitted(S10). After a predetermined time, the data burst message is loaded on the corresponding slot in accordance with the transmission slot information so as to be transmitted (S11).
Meanwhile, when a data burst message is transmitted through a broadcast control channel(BCCH), a base station transmits the data burst message through the broadcast control channel. In order to inform the slot in which such a broadcast message is transmitted, the base station firstly transmits the broadcast page through a forward common control channel(F-CCCH).
When the broadcast message is transmitted thorough the broadcast control channel BCCH, the base station transmits the data burst message through the broadcast control channel. In order to inform the slot in which such a broadcast message is transmitted, the base station transmits an enhanced broadcast page through the forward common control channel(F-CCCH).
Correspondingly, a mobile station determines whether to receive the broadcast message using a burst type and a broadcast address of the enhanced broadcast page. A value of the broadcast address is determined by a demand condition of a Standard in connection with the burst type.
The enhanced broadcast page informs a broadcast address type and a broadcast message scheduling information with a record in a general page message or a universal page message.
The enhanced broadcast page is transmitted only once during a broadcast paging cycle. In each broadcast paging cycle, the enhanced broadcast page exists on a first forward common control channel slot. A forward common control channel slot through which the enhanced broadcast page is transmitted is defined as a reference slot. A first transmission of the broadcast message is transmitted on the broadcast control channel slot located behind the reference slot to the extent of 40 ms×(1+TIME_OFFSET). And, a retransmission is transmitted on the broadcast control channel slot located behind the first-transmitted broadcast control channel slot to the extent of 40 ms×(1+REPEAT_TIME_OFFSET).
In FIG. 1, data transmission rates of the paging channel PCH are 4.8 kbps and 9.6 kbps respectively. In case of 4.8 kbps, it is able to transmit 96 bits in one frame of 20 ms. Thus, it is able to transmit 384 bits, i.e. 48 bytes, on a single slot of 80 ms. In case of 9.6 kbps, it is able to transmit 192 bits in one frame of 20 ms. Thus, it is able to transmit 768 bits, i.e. 96 bytes, on a single slot of 80 ms.
Data transmission rates of the broadcast control channel are 4.8 kbps, 9.6 kbps, and 19.2 kbps. In accordance with the respective data transmission rates, the sizes of the slots are different as 160 ms, 80 ms, and 40 ms, respectively. Yet, each amount of data transmitted on a single slot is 744 bits, i.e. 93 bytes.
In case of the present data burst message, a message is transmitted through a traffic channel when a message length msg_len of an IPC header is over 63 bytes(504 bits). Instead, the message is transmitted through a paging channel when the message length msg_len of the IPC header is under 63 bytes(504 bits). The maximum number of characters enabling to be transmitted through the paging channel according to a related art is found by “M=504 bits-98 bits(msg_type, ARQ, Address, SDU)=406 bits=406/8 bytes=50.75 bytes”. Considering a padding only, it is able to transmit data of 50 bytes as the maximum number of the characters.
Therefore, it is impossible to a broadcast message such as a video requiring transmitting a data having large traffic volume through the present paging or broadcast control channel. Instead, when a transmission rate of the broadcast message is required higher than a predetermined data rate, the broadcast message may be transmitted through the traffic channel. Unfortunately, the broadcast message has to be transmitted inconveniently to the entire mobile stations respectively so as to use the traffic channel.